This doctoral dissertation examines the mutual relationship between epistemological beliefs and fostering information literacy skills in the context of higher education. By reviewing recent literature, a lack of questionnaires measuring epistemological beliefs appropriately in the context of higher education is identified. Although currently available questionnaires are capable of distinguishing between absolute and non-absolute epistemological beliefs, they are not capable of distinguishing between non-differentiated and differentiated multiplistic beliefs. Therefore, the dissertation is subdivided into two parts. In the first part, a new epistemological questionnaire consisting of items with absolute and multiplistic statements is developed (four studies, total N = 416). In the second part, the impact of epistemological beliefs on learning gains in a blended learning training to foster information literacy skills of psychology students is examined by employing the new epistemological questionnaire and a multiple-choice information literacy knowledge test (N = 67). Furthermore, short-term changes in epistemological beliefs depending on participation to the training are investigated. Factor analyses reveal absolute and multiplistic items to load on different factors. The final factor solution comprises k = 23 items loading on two factors. Items with absolute statements predominantly load on the first factor, whereas items with multiplistic statements predominantly load on the second factor. The two resulting scales show a satisfying internal consistency. Convergent validity of both scales is evidenced by significant correlations with the two scales of the questionnaire &quot;Connotative Aspects of Epistemological Beliefs&quot; (CAEB) as well as with the scale &quot;Need for Cognitive Closure&quot; (NCC). Cross-sectional analyses show significant lower means of the multiplistic scale with increasing study progress, whereas the means of the absolute scale do not differ significantly. Multiple regressions reveal multiplistic beliefs to be obstructive for learning gains, whereas absolute beliefs appear to have no significant impact. Absolute beliefs significantly increase dependent on training participation, whereas multiplistic beliefs appear not to be affected by the training. The results suggest that considering multiplistic beliefs separately leads to more detailed information about epistemological beliefs among students in higher education (e. g. about the development of epistemological beliefs). Furthermore, the results support the assumption of a mutual relationship between epistemological beliefs and fostering information literacy skills. This relationship might be attributable to an absolute nature of learning contents about information literacy.